Does anyone know what TBMs are used for this? Presumably the ones from the Chilterns tunnels will be knackered.
As I understand it, TBM's are like race cars - they're built "just good enough" to do the job required. Some bits of them are salvaged and reused, but substantially each TBM is built bespoke for the job in hand then thrown away (sometimes literally - cutters get buried for example.) Not to mention that they have to be customised for the ground conditions, diameter, etc.
Also, the Long Itchington TBM is presently programmed to start in June 2021 whereas the Chiltern TBM's are not expected to finish until 2023, so clearly there's programme overlap.
There's 10 TBM's on order for the main running lines - 2x for OOC-Euston, 4x for OOC-West Ruislip (dug from both ends and meet in the middle) 2X for Chilterns, 1x for Long Itchington (digs both bores) and 1X for Bromford (digs both bores) plus possibly a smaller one for a temporary "logistics tunnel" between the OOC station box and the Willesden "Eurotunnel" railhead. And some tiddlers for utility diversions (gas/water at Harvil Road for example.)
Culled from various documents in the public domain over the years, most recently the HS2 Ltd Corporate Plan (link below) my most up to date estimate of approximate TBM launch dates is 2023-Dec for OOC-Euston, 2022-Jun Northolt, 2021-Apr Chiltern, 2022-Mar Bromford, 2021-Jun Long Itchington.
The Corporate Plan includes a review of performance in 2019/20 and sets out our key objectives and a high-level delivery plan for the 3 years to 2022/23. Some of the information you will find in the Corporate Plan includes: our vision, mission and values key facts our approach how we measure our...
www.hs2.org.uk
When do we actually find out if the line will get built to Leeds/Sheffield?
I would suggest when a Bill is deposited in Parliament and said Bill has passed the "second reading" vote. Forgive me if I'm teaching Granny to suck eggs, but for the avoidance of doubt, second reading is the vote that "matters" in Parliamentary proceedings and technically Parliament could knock down a Bill in subsequent stages, but it rarely happens once a second reading vote has succeeded.
Of course, once such a Bill has passed through Parliament (and become an Act or Parliament) the Government could cancel or by de facto cancel it by not funding it, but if would be difficult politically to do so when Parliament has expressed it's will, not to mention the present Tory government needs to do everything it can to be seen to deliver on it's promises to new found chums in the North.